Pupil

Course Information

About This Track

System design asks a different question from DSA: not “what is the fastest algorithm” but “what happens when ten million people use this at once”. The track is split into high level design — the boxes and arrows of a large system — and low level design, which is clean object oriented code and design patterns.

The reading list is built on the open source System Design Primer repository on GitHub and the GeeksforGeeks system design tutorial. Design patterns are studied from Refactoring Guru, and every case study ends by comparing our design with a real engineering blog.

What You Will Learn

• Estimate traffic, storage and bandwidth before drawing anything
• Scale a system horizontally with load balancers and stateless servers
• Choose the right cache strategy and handle cache invalidation
• Decide between SQL and NoSQL, and shard or replicate a database
• Apply the CAP theorem and explain the trade-off you accepted
• Write clean LLD with SOLID principles and the common design patterns

Syllabus

Code From The Lab

Sample from Module 5 — Strategy pattern in the LLD module

// One payment service, many payment methods - no if-else chain.
interface PaymentStrategy {
    void pay(double amount);
}

class UpiPayment implements PaymentStrategy {
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using UPI");
    }
}

class CardPayment implements PaymentStrategy {
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using card");
    }
}

class Checkout {
    private PaymentStrategy strategy;                  // open for extension,
    Checkout(PaymentStrategy s) { this.strategy = s; } // closed for modification
    void placeOrder(double amount) { strategy.pay(amount); }
}

Video Lectures

Click the thumbnail to open the video playlist for this track:

Recorded College Session

Video Playlists

• ByteByteGo — Short animated explanations of every core system design concept
• Gaurav Sen — Long form system design interview walkthroughs
• System design case studies — Mock interviews and case study playlists

Open Source Study Material

These are the exact open sources the notes for this track are prepared from.

Lab Projects

1. Design a URL shortener and defend your ID generation choice
2. Design a rate limiter and implement the token bucket in code
3. LLD of a parking lot or a splitwise clone with UML diagrams
4. Re-design one of your own earlier projects for 1 million users

Your Progress

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